This proposal is continued support for the Pediatric Oncology Group Statistical Office. The capabilities of the office include the development of statistical considerations and design parameters for new protocols, implementation of mechanisms through which patients may be registered, the compilation, processing and analysis of data to answer protocol questions. The Statistical Office engages in methodologic research applied to cooperative study groups and randomized clinical trials. It assists the group in formulating research questions through analyses of risk factors, prognostic indicators or estimates of patient accrual. The staff of the office serve on all Pediatric Oncology Group committees with major administrative responsibilities, providing direction in specific disease, discipline and organizational aspects of the activities of the group. The Statistical Office also contributes to the quality assurance mechanisms implemented within the group and serves as a repository for patient files.